Pneumatic piano-player.



J. L. FORSTER. PNEUMATIG PIANO PLAYER.

APPLIOATION FILED D3014, 1910.

1,033,000. Patented July 16, 1.912

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PNEUMATIC: PIANO-PLAYER.

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Specification of Letters Patent.

Patented July 1 1912.

Application filed December t4, 1910. Serial No. 597,357.

To all whom it may concern:

Be it known that I, Josnrn L. Fousrnn, a citizen of the Dominion of Canada, residing at Vancouver, in the Province of British Columbia Canada, ha e invented anew and useful Pneumatic Piano-Player, of which the "following is a specification.

This invention relates to an improvement piano players and is designed to enable the tone of the notes sounded to be varied or shaded by the operator when the pneumatic regulator is in use.

In pneumatic piano players what is termed the pneumatic. regulator merely gives the efl'ect of a more delicate touch bv providing a means for maintairiug a less vacuum in the air chest from which the power pneumatics are served than is maintained in the reservoir of the main bellows, but as the pneumatic regulator is usually made in the maintenance of this less vacuum all power of varying the tone, while playing or giving proper expression to the music, is lost and although a lighter tone is obtainable it is maintained at. a dead level. he cause of this is due to the use of a coiled spring as a counterbalance to the controlling area which maintains .the desired less vacuum in the air chest of the power pneumatics. To obviate this objection I substitute for the tension of a coiled spring a device which is ex posed to the vacuum in the main reservoir, and as this vacuum may be varied at will by the party .who is playing, so the lighter vacuum in the air chestmay be correspondingly varied,

The invention is particularly described in the following speclfication, reference being made to the drawing by which it is accom-' panied, which represents a section through an expression box such as is commonly used to reduce the tone, when desired, showing the application thereto of the supplementary device by which I attain the desired object. v

In this drawing 2 represents a pneumatic regulator of ordinary design, 5 being the connection to it from the air chest or duct which serves the power pneumatics and 4 the port delivering from the box to the pipe 3 which connects it to the main bellows reservoir. It must beundcrstood that this pneumatic regulator is only re uired to be used when a more delicate touci is desired in the music which delicacy of touch is attained by maintaining a less vacuum in the power pneumatics than can be maintained in the'main vacuum reservoir. This control of the vacuum within the pneumatic regulator and its duct 5 is exercised by a knife valve 7 pivoted at S to close over the portt and cut. off ,connectionwith the reservoir when the pressure due to the vacuum exceeds a certain predetermined point. \llith this object. the knife valve 7 is connected-by a link 9 to the free end of a movable member 6 which is connected by afiexible fabric to the walls of the box 2-.

In the pneumatic regulator as usually constructed, the movable memliigr G is normally held at the outer limit of its movement by a coiled spring in which position the port 4 is uncovered by the valve 7 and .when the desired limit of vacuum is attained in the pneumatic regulator whicli limitis less than what is obtainable in themain bellows, the spring is overcome and thegvalve restricts communication with the main reservoir until the pressure due to the vacuum in the pneumatic regulator becomes too lightto sustain the tension of thespring when the movable member 6 movesputwaid and the port 4 is further uncovered. In using a coiled spring to control the movement of the valve 7 th t control is such that the vacuum in the pneumatic regulator itself and its connected power pneumatics is so constant as to be objectionable as the person playing has no-power,. while playing, to

vary the vacuum vso as to shade thetone which is maintained at a dead level. It is to remove this objectionable characterist-ic of the pneumaticregulator as used, that my invention has been devised. Broadly thatimprovement consists in dispensing with the spring control and in substituting therefor a control exercised by a supplementary vacuum chamber 10 one side of which 11 is connected so as to he movable in a similar manner to that of the pneumatic regulator, to which member 6 the free end of 11 is connected so that they act in opposition to one another. The area-of 11 is less than that of 6 so that in practice the vacuum of the main reservoir acting on the area of 11 is opposed to the desired lighter vacuum in the pneumatic regulator 2 acting on the larger area of its bottom 6. The principle of action is the same, in that the vacuum in the power pneumatics is controlled by a valve 7 which will close when the desired limit of vacuum is attained, but instead of measuring this vacuum in the mainy'reservoir is susceptible of variation by the operator withln a-wide ment :of 10 cised will be varied.

limit /by the constant tension of a coiled spring I substitute an area acted on by the vacuum ofithe main reservoir and as the range, that range of variation 15 expressed in the lighter vacuum which it is desired shall act when the pneumatic regulator is in use. In order to enable the ratio ot the control to be varied by adjustment as required the control chamber 10 may be made susceptible of endwise niovement in its attachment to the fixed bracket 14: on which it is-supported and may be secured in any desired position of endwise adjustment, This in the drawing is shown as attained by a butterfly nut 15 in an elongated hole in a strip secured to the bottom of the chamber, but may be attached to a member movable from the keyboard. Connection to the free end of 11 is made to the free end of 6 in a manner that will permit of endwise move- I in relation to 2. This may be done'as shown in the drawing by a projecting rod 16 secured to 6 which rod passes through aneyelet 17 secured to the free end of 11. The controlling chamber 10 may thus be moved endwise to act at agreater or less leverage in its connectionto'6 and the limit of the vacuum at which the control is exer- I do not desire to be confined to the particular construction here set forth by; which control of the vacuum in the power pneumatics is exercised by the vacuum in the main reservoir as I consider I am entitled to protect-ion in the broad idea of maintaining a less vacuum in the power pneumatics which maintaining means is controlled by the vacuum of the main reservoir.

Having now particularly described my invention and the manner of its use, I hereby tively,

declare that what I claim as new and de sire to be protected in by Letters Patent, is:

In a pneumatic piano player, the combination with the power pneumatics, the main reservoir, the pneumatic regulator and the ducts between theregulator and said power pneumatics and said main reservoir respecsald pneumatic regulator including a pivoted gate valve for controlling the passage to the main reservoir proportionately as said valve ismoved, said pneumatic regulator including a movable member and a connection between said movable member and said valve, means for moving said movable member and said valve to maintain a lighter vacuum in the power pneumatics than prevails in the main reservoir, said means comprising a supplementary bellows of less capacity than that of the pneumatic regulator, and ducts connecting said bellows with the main reservoir, together with a perforated member rigidly mounted on the movable member of said supplementary bellows, and a rod on said first mentioned movable member, projecting through said per-- :torated member to connect saidfirst mentioned movable member with the movable member of said supplementary bellows, in virtue of which, the movement of either movable member will be imparted to the other movable member, and means for mounting said supplementary bellows to vary the point of connection between said movable members.

In testimony whereof I have signed ,my name to this specification in the presence of two subscribing witnesses.

JOSEPH LESLIE FORSTER.

Witnesses ROWLAND BRITTAIN, WM. S. SOUTAR.

Copies at this patent may be obtained for five cents each, by addressingthe r 1 Washington, D. G. I

Commissioner" of 2mm, 

